The present invention relates to a working vehicle for construction works and civil engineering works, and more particularly to a working vehicle including a traveling warning system for informing persons around the working vehicle that the working vehicle is in the traveling state is provided.
Conventionally, there is a working vehicle, in which a traveling warning system is provided so as to warn (usually sound an alarm) operators and passersby around the working vehicle of a traveling state of the vehicle such as a forward and rearward movement, a turn, etc.
For example, as shown in an art disclosed in the Japanese Utility Model Laid Open Gazette Sho. 61-89065, a traveling warning system is installed in a working vehicle, and constructed in such a way that a traveling lever operated by an operator is mechanically connected with an operation switch of the traveling warning system, and a warning sound generator is operated by being interlocked with the traveling lever.
Moreover, as shown in an art disclosed in the Japanese Utility Model Laid Open Gazette Sho. 61-93562, there is also a working vehicle, which is constructed in such a way that the traveling warning system is operated by detecting the pressure of a hydraulic circuit for traveling.
However, in case of the art disclosed in the Japanese Utility Model Laid Open Gazette Sho. 61-89065, there is some possibility that the earth and sand, a stone, etc. are caught in between the traveling lever and the operation switch, thereby leading to the malfunction of the traveling warning system.
In case of the art disclosed in the Japanese Utility Model Laid Open Gazette Sho. 61-93562, it is necessary that two pressure switches are provided, thereby leading to an increase of parts and costs.
When the warning is performed by sound, in consideration of the maximum noise generated in the work by the working vehicle, a sound generator generating a loud warning sound is provided in the working vehicle so as to overcome the noise. Therefore, as the case may be, the warning sound itself becomes such a noise as to bring a noise pollution to the residential section around the job site.
In order to cancel this discrepancy, there is a working vehicle enabling free cancellation of the warning by a canceling switch provided in the warning sound generator. However, once the warning is cancelled, the warning sound is not generated in case of changing into the next working or generating the warning again, so that the warning sound generator is not useful as a safety device.
An object of the present invention is provide a working vehicle equipped with a pair of hydraulic traveling motors for driving left and right traveling devices, a pair of hydraulic directional control valves for controlling the respective traveling devices, and a traveling warning system for warning persons around the working vehicle that the working vehicle is in a traveling state, wherein the traveling warning system is improved so as to prevent the wrong operation thereof led by the external exposure of a traveling detecting element for detecting that the working vehicle is in the traveling state, and to decrease the number of parts and costs.
In order to attain this object, in the working vehicle according to the present invention, a traveling warning system comprises a throttle valve provided in a pilot oil-passage so as to feed pilot-oil to a hydraulic pilot type control device provided in the working vehicle, and connected to a low pressure oil-passage after passing serially through the pair of hydraulic directional control valves below the throttle valve. The traveling warning system further comprises a pressure switch operated by the hydraulic pressure within an oil-passage between the throttle valve and an upstream side one of both the hydraulic directional control valves, and a warning device operated on the basis of the on-off of the pressure switch.
Due to the present invention, the pressure switch serving as a traveling detecting element of the traveling warning system is installed inside the working vehicle so as not to be exposed outward, thereby being protected from the earth and sand, a stone, etc. causing wrong operation thereof, and enhancing the reliability as a warning device. Since the pair of the hydraulic directional control valves for controlling the hydraulic traveling motors are serially disposed in the pilot oil-passage, only one pressure switch is sufficient to detect the situation that at least one of the pair of the traveling motors is driving, thereby reducing the number of parts and costs.
A second object of the present invention is to provide a working vehicle, where a traveling warning system, which alarms surrounding persons that the working vehicle is in a traveling state, with a warning sound in a suitable volume corresponding to any situation without depending on a canceling switch of the warning.
In order to attain this object, in a working vehicle according to the present invention, a traveling warning system includes a detector detecting whether the working vehicle is in the traveling state, a warning sound generating means electrically connected with an output contact of the detector, and a controller provided in the warning sound generating means.
Therefore, it is possible to control the sound volume so as to correspond to various environments around the job site. For example, the volume is decreased in a residential area etc., while the volume is increased in a work site where a loud noise is generated (or may be generated) so that the noise does not drown the warning sound. Especially, since the warning sound in the traveling warning system is not controlled by alternative steps of generation and cancellation of the warning sound, but controlled by gradual steps from a loud sound to a low sound, it is possible to prevent the generation of a noise pollution by the low warning sound even in case of the job site where the restriction of noise is expected, thereby ensuring that the traveling warning system always functions as means for a safety precaution.
Moreover, a plurality of warning sound generators having different sound volumes are provided in the warning sound generating means. The sound volume control is performed by selecting one from the plurality of warning sound generators without a complicated control circuit etc., thereby enabling an expected sound volume to be output immediately, and simplifying the warning sound generating means and reducing costs thereof.
The above and other objects of the invention will become more apparent from the following detailed description based on the accompanying drawings.